Prosthetic heart valves are used as a replacement for natural heart valves of patients. A standard implantable mechanical heart valve typically includes an annular valve housing or body (often called an "annular body") to provide a lumen or passageway therethrough for blood flow. One or more occluders mounted to the valve are movable in response to blood flow between an open position, allowing blood flow, and a closed position, which stops or blocks blood flow in one direction. In many mechanical valves, the occluders are essentially plate-like flat or curved members called "leaflets." Typical configurations include one, two or more leaflets in the valve body.
There has been an ongoing effort to improve the efficiency of prosthetic heart valves. One critical factor in heart valve efficiency is the total area through which blood can flow when the valve is in the open position. One factor which limits the total area is how far that the leaflet(s) can open during normal operation of the valve. The more that the leaflet(s) can open to a direction that is parallel with the flow, the more efficient the valve becomes. U.S. Pat. Nos. 5,192,309 and 5,350,421 show a technique which uses a sliding pivot to increase the leaflet opening angle. However, this technique required a complex mechanism which tended to fail in actual use.